H. Roginski

The effect of bovine lactoferrin and lactoferricin B on the ability of feline calicivirus (a norovirus surrogate) and poliovirus to infect cell cultures

Aims: To characterize the effect of bovine lactoferrin and lactoferricin B against feline calicivirus (FCV), a norovirus surrogate and poliovirus (PV), as models for enteric viruses.

The effects of refrigerated storage of raw milk on the quality of whole milk powder stored for different periods

Abstract Whole milk powders were produced from fresh (control) and stored (4 ± 1 °C, 48 ± 2h) raw milk in three seasons (spring, summer and autumn), and stored for up to 8 months at 25 ± 1 °C. The suitability of the milk powders for reconstitution processes was assessed on the basis of selected microbiological, physical, chemical and biochemical quality parameters. Storage of raw milk did not significantly affect total bacterial count (TPC) in the resultant powder. Free fatty acid (FFA) content in powder manufactured from stored raw milk was greater than that from the control. TPC and free fat content decreased while insolubility index, FFA and peroxide value increased during storage of powder; lipase and proteinase activities did not change. All powders manufactured from control and stored raw milk, and stored for up to 8 months, were found suitable for reconstitution on the basis of TPC, moisture content and amount of scorched particles but not based on insolubility index.

Alternative disinfection techniques to extend the shelf life of minimally processed iceberg lettuce.

Chlorination continues to be widely used by the fresh-cut industry for washing and disinfecting minimally processed fruits and vegetables. However, as chlorination has been reported to produce unhealthy by-products such as, chloramines and trihalomethanes, many alternative methods have been reported in the literature. This study examined the use of silver and hydrogen peroxide as possible alternative to chlorination. The results revealed an obvious bactericidal effect of hydrogen peroxide, silver and their combination on spoilage organisms. Combination of electrochemically generated silver (5 ppm) and hydrogen peroxide (0.4 ppm) caused significant (P < 0.05) reduction in the total plate count (0.87 log), Pseudomonas (2.66 logs), Enterobactericeae (1.61 logs) and yeast and mould (1.60 logs) immediately after washing in comparison to water washed shredded lettuce. However, washing with chlorinated water (5 ppm) under same conditions revealed insignificant reduction in TPC (0.17 log), Pseudomonas (0.60 log), Enterobactericeae (0.15 log) or yeast and mould (0.81 log) counts. Results revealed also that both sources of silver (electrochemical silver and silver nitrate) have similar disinfecting effects, however, electrochemical silver maintained the quality of washed lettuce.

Reconstituted UHT-treated milk: Effects of raw milk, powder quality and storage conditions of UHT milk on its physico-hemical attributes and flavour

Abstract Reconstituted, UHT-processed milk was produced from whole milk powders that were manufactured from fresh (control) or stored (4 ± 1 °C, 48 ± 2 h) raw milk and stored for different periods at 25 ± 1 dgC. Lipolytic and proteolytic activities, physico-chemical and flavour changes and gelation in UHT milk during storage at 3 ± 1 °C or 25 ± 1 °C for up to 6 months were investigated in relation to the biochemical status of raw milk and whole milk powder. The green-red and blue-yellow components of colour and the non-protein nitrogen content of UHT milk increased, while pH and colour lightness decreased with storage; the rate of change being greater at higher storage temperature. Sediment increased with longer storage period, but was independent of storage temperature. With longer storage at both 3 ± 1 °C and 25 ± 1 °C, greater sediment and lower pH were observed in UHT milk processed from older milk powders. Rates of enzymatic and oxidative reactions appeared greater in UHT milk stored at 25 ± 1 °C and in those processed from older powders and contributed to the development of off-flavours in UHT milk with a prolonged storage period. Gelation was observed only at 25 ± 1 °C. Lipases and proteinases were reactivated during storage and their activity was greater in UHT milk processed from powder manufactured from stored raw milk. The taste of reconstituted UHT milk was affected more by lipolysis than by proteolysis.

Comparison of the effects of acylation and amidation on the antimicrobial and antiviral properties of lactoferrin

Aims:  To compare amidation and acylation of lactoferrin (LF) from bovine milk, as a means of enhancing its antimicrobial and antiviral properties.

Effect of the Ionic Strength of Pulsed Electric Field Treatment Medium on the Physicochemical and Structural Characteristics of Lactoferrin

Pulsed electric field (PEF) treatment (35 kV cm(-1) for 19.2 μs using bipolar 2 μs pulses) was conducted on bovine lactoferrin (LF; 0.4 mg mL(-1)) prepared in simulated milk ultrafiltrate (SMUF), at concentrations between 0.2× and 2× normal strength, with electrical conductivities ranging from 0.17 to 1.04 S m(-1). The physicochemical and structural characteristics (LF content by a spectrophotometric and an ELISA method, surface hydrophobicity, electrophoretic mobility, far-UV circular dichroism spectra, and tryptophan fluorescence) of LF dissolved in SMUF of all strengths tested were not changed after PEF treatment. The PEF treatment of LF in 0.2 strength SMUF did not cause the release of LF-bound ferric ion into the aqueous phase, with a concentration of LF-bound iron being the same as that of the untreated LF control (174 μg L(-1)). However, in treatment media with higher ionic strengths, ferric ion was released from the LF molecule into the aqueous phase. The concentration of LF-bound iron decreased from 174 μg L(-1) for the LF treated in 0.2 strength SMUF to 80 μg L(-1) for that treated in double-strength SMUF. The results suggest that the PEF-induced iron depletion of LF does not appear to cause an appreciable conformational change in LF molecules. PEF treatment could be developed as a novel physical way to produce iron-depleted LF, as an alternative to the existing chemical method.